The green bike helmet is a good solution, I like that. I should point out that BrickArms and BrickForge both also have military helmets, if you don't mind custom pieces, although they're pricey ($1-$1.50 each).

Olothontor wrote:One question about that silo... I can't identify those red bits on top of the cylinder pieces. What are those?

they're the base of minifig joysticks/antennas. they've got the stick part taken out, and then they're placed on top of those 1x1 grey pins with one end that's about half length. what's great about these rockets, is that they're removable; they fit into the hollow chamber of those 1x1 cylinders, and function as excellent firing chambers (so you can actually "launch" the rockets!)